Activate any number of lands except Urza's Saga by tapping them, adding at least {2}.
Activate Urza's Saga's second ability by paying {2} and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to Arwen's toughness.
When the Construct enters the battlefield, Verdant Sun's Avatar triggers, causing you to gain at least 10 life.
Activate the Construct using Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Repeat.
If other lands you control can tap to produce at least {3}, this combo nets infinite mana.

Infinite colored mana

Infinite creature tokens

Infinite creature ETB

Infinite lifegain

Infinite lifegain triggers

Infinite power and toughness for certain creatures

Infinite mana lands you control can produce

Infinite untap of lands you control

Beledros Witherbloom

Urza's Saga

Agatha's Soul Cauldron

Arwen, Weaver of Hope

Verdant Sun's Avatar

Activate any number of lands except Urza's Saga by tapping them, adding at least {2}.
Activate Urza's Saga's second ability by paying {2} and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to Arwen's toughness.
Activate the Construct using Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Activate the Construct using Gristleback's ability by sacrificing it, causing you to gain at least 10 life.
Repeat.
If the number of artifacts you control plus Arwen's toughness is equal to or greater than 10, this combo nets infinite life, and if other lands you control can tap to produce at least {3}, this combo nets infinite mana.
If you get infinite life and infinite mana, you may forego sacrificing the Constructs.

Infinite death triggers

Infinite creature LTB

Infinite creature sacrifice triggers

Gristleback

Activate any number of lands except Urza's Saga by tapping them, adding at least {2}.
Activate Urza's Saga's second ability by paying {2} and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to Arwen's toughness.
Activate the Construct using Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Activate Diamond Valley by tapping it and sacrificing the Construct, causing you to gain at least 10 life.
Repeat.
If the number of artifacts you control plus Arwen's toughness is equal to or greater than 10, this combo nets infinite life, and if other lands you control can tap to produce at least {3}, this combo nets infinite mana.
If you get infinite life and infinite mana, you may forego sacrificing the Constructs.

Diamond Valley

Activate any number of lands except Urza's Saga by tapping them, adding at least {2}.
Activate Urza's Saga's second ability by paying {2} and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to Arwen's toughness.
When the Construct enters the battlefield, Angelic Chorus triggers, causing you to gain at least 10 life.
Activate the Construct using Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Repeat.
If other lands you control can tap to produce at least {3}, this combo nets infinite mana.

Angelic Chorus

Activate any number of lands except Urza's Saga by tapping them, adding at least {2}.
Activate Urza's Saga's second ability by paying {2} and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to Arwen's toughness.
When the Construct enters the battlefield, Trostani triggers, causing you to gain at least 10 life.
Activate the Construct using Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Repeat.
If other lands you control can tap to produce at least {3}, this combo nets infinite mana.

Trostani, Selesnya's Voice

Cast Auramancer from your graveyard for its retrace cost by paying {W} and discarding Urza's Saga.
When Auramancer enters the battlefield, it triggers, returning Urza's Saga from your graveyard to your hand.
Activate Phyrexian Altar by sacrificing Auramancer, adding {W}.
Repeat.

Combos with "Urza's Saga"